Answer:
P(X is less than 348) = 0.2148
Explanation:
Given that:
Sample proportion (p) = 0.3
Sample size = 1200
Let X be the random variable that obeys a binomial distribution. Then;

The Binomial can be approximated to normal with:


To find:
P(X< 348)
So far we are approximating a discrete Binomial distribution using the continuous normal distribution. 348 lies between 347.5 and 348.5
Normal distribution:
x = 347.5,
= 360,
= 15.875
Using the z test statistics;



z = -0.7874
z ≅ - 0.79
The p-value for P(X<347.5) = P(Z < -0.79)
From the z tables;
P(X<347.5) = 0.2148
Thus;
P(X is less than 348) = 0.2148